Adjustable lamp mount



Patented May 29, 1951 ADJUSTABLE LAMP MOUNT James Lawrence Pettus,Sherman Oaks, Calif., assignor to Radio Corporation of America, a

corporation of Delaware Application April 2, 1947, Serial No. 739,007

6 Claims. 1

This invention relates to optical systems and particularly to anadjustable mounting unit for a light source used in optical systems.

In many optical systems, such as those employed in recording soundphotographically on film, the light source is usually a lamp having asubstantially horizontal filament, the positioning of the filament withrespect to the optical axis of the system being critical to provide auniformly narrow beam of light across the sound track area. Adjustablemountings for such light sources have been used in the past to permitthe filament to be placed on the optical axis of the unit and at aposition which provides the maximum of light quanta to be focussed onthe modulator and the most uniform distribution of the light over thearea to be illuminated. Such a three way adjustable lamp mount isdisclosed and claimed in Ross U. S. Patent No. 2,093,023, of September14, 1937.

The present invention, however, is an improvement over the Rossconstruction, particularly for lamp light sources of sound recordingsystems or the exciter lamps of sound reproducing systems. The inventionpermits the less critical adjustments to be made during the constructionof the mount which then may be permanently fixed while providing asimple and sensitive control for the critical adjustment which "isgenerally necessary, particularly when lamps are changed.

To aid in positioning the filament of such a light source at the properposition with respect to the optical axis, pre-focus lamps are used,such a lamp having an aperture plate fixedly attached to the lamp basewhich positions the filament at a certain distance from the plate whenthe lamp is placed in its socket. However, the distance between the lampfilament and the pre-iocussing plate is not uniform in all lamps andconsequently a readily and accurately adjustable mount for the verticalposition of the filament is required. This adjustment may also be madein the event a filament sags after it has been in use.

The principal object of the invention, therefore, is to facilitate theadjustment of a lamp light source in an optical system.

Another object of the invention is to provide an improved adjustablelamp mount.

A further object of the invention is to provide an improved lamp mountfor simply and accurately adjusting the filament of the lamp in severaldirections.

A still further object of the invention is to 2 provide a lamp mountwhich provides a fine degree of adjustment of a lamp filament to alignit with the optical axis of an optical system.

Although the novel features which are believed to be characteristic ofthis invention will be pointed out with particularity in the appendedclaims, the manner of its organization and the mode of its operationwill be better understood by referring to the following description readin conjunction with the accompanying drawings forming a part hereof, inwhich:

' Fig. 1 is a plan view of a lamp mount embodying the invention andshown in relation to the other optical elements of a sound recordinsystem;

Fig. 2 is a cross sectional view of the invention taken along the line2-2 of Fig. 1; and

Fig. 3 is a cross sectional view of the invention taken along the line33 of Fig. '1.

Referring now to the drawings in which the same numerals identify likeelements, the lamp mount of the invention consists of a casting 5 havingapproximately a circular configuration and extensions 6, l and 8. Thecasting is mounted in an opening in a base partially shown at 9. Thereare a pair of elongated slots It and II in casting 5 diametricallyopposite one another and in which are a pair of screws l2 and I3,respectively, the slots also being wider than the shanks of the screwsfor a purpose explained hereinafter. A lamp [5 is shown in position inthe mount, the lamp providing light flux for a sound recording opticalsystem employing a lens I6, a modulating element such as a galvanometerH, a noise reduction unit 3 and a film [9". The noise reduction unit I8is disclosed and claimed in my copending application Serial No. 739,484,filed April 4, 1947, now Patent No. 2,452,322, issued October 26, 1948.

It is realize that to provide the proper illumination for the modulatingmirror of the galvanometer I! and the noise reduction unit [8, thefilament 2| in the lamp [5 should be accurately aligned with the opticalaxis shown by the broken line 22. It is also necessary that the filament2| be properly orientated with respect to the optical axis 22, that is,the axis of the filament should be normal to the optical axis. It isalso necessary that the filament be in the correct position along theoptical axis to provide the maximum amount of light on the galvanometermirror. The present invention provides all of these adjustments in asimple and efiicient manner.

Referring now particularly to Figs. 2,, and 3,

the casting 5 has a circular opening therein in which is inserted thelower portion of a vertically adjustable member 25 which has its lowernarrow portion 26 externally threaded and its upper and larger diametersection 21 externally threaded. The section 25 is keyed to the casting 5by a key 29 to prevent relative'rotation therebetweenbut permittinglongitudinal, or axial adjustment therebetween. Positioned within thecircular recess in the large diameter section 10,

21 is an insulating collar 3| which is attached" to the adjustablemember 25 by two bolts and 34; (See Fig. 3.) Also passing through thecollar 3| at 90 from the bolts 33 and Stare two more bolts 35 and 35(see Fig. 2), the bolt 35115 fastening an electrical contact spring 38,which has a contact element 39 at the'end thereof and located in thecenter of the insulator 3|, for

ti 'ical conductor may be attachedin any suitable 2 manner, the plate Mhaving an opening therein to" permit-the passage therethrough of' thebase 45 6f the lamp I 5.

Positioned under the ring 44 and between this ring and the springcontactor 38, is a second 0 plate or ring 47 having an opening thereinto accommodate the base 45 of the lamp i5 and which is mounted on threeequidistantly spaced pins, two of which are shown in Fig. 2 at 59 and50. These pins have enlarged upper ends 5| and 35 52' while surroundingthe narrow portion of the pins are coil springs 54 and 55 which act topull the ends 5| and 52 against the plate 44. The lamp I5 is providedwith the usual pre-focusdisc or ring 51 having three tapered holes 58therein,

the'larger portions of the holes permitting the heads 5| and-52 ofpin's49 and 55 to pass therethrough, so that the ring 51 can contact theplate M. Now; if the lamp I5 is twisted, the narrow portion of theopenings 58 will pass under the heads 5| and 52 of the bolts and thesprings 54 and 55 will hold the lamp firmly in position, the contactterminal H of the lamp contacting the ooiitacto'r 39 of the spring 58.

The pre focus rings 51 are generally attached to the lamp bases 45 insuch a manner that when adjusted in position under the pin heads, thefilamenus will always have the same spatial relat'ion'ship However, alllamps are not suflic'ient 1y uniform in all respects to completely avoidall adjustment and it, therefore, becomes necessary 'at' tiines toslightly vary the 'lamps position.

The less critical adjustments are those for varyin the filament positionalong the optical axis and perpendicular to it and most lamps varylittle in filament placement within the lamp. However, as mentionedabove, these adjustments must beprovided for, but can be made duringconstruction. They are accomplished by looseni d since the elongatedholes H! and 'II are w er than the shanks 'of the screws l2 and I5,rotational adjustment of the casting 5 may be made O'i'l the base tobring the axis of the "filaineiit Z I perpendicular to the axis "22. Toproper- 76 av place the filament 2| along the optical axis, tlicasting'5 may be 'moved along the length of we emngatea holes 10 and H. Withthese "two adjustments made the screws [2 and i3 may be tightened in thebase to hold the lam-p these T An electrical supply 20 the screws I2 andi3 threaded into the base erally caused by the variations in theposition of attachment of the rin 5! to the lamp base 45 betweendifferent lamps. Furthermore, a lamp filament may sag when heated orafter hours of use. There is need, therefore, to frequently raise and"lower the lamp |5 to accurately position the filament in 'the plane ofthe optical axis 22. This accomplished. with the present invention in asimple manner, but one which provides a fine and-accurate control.

Referring again to Figs. 2 and 3, the longitudinally adjustable member"25- is: held. in position by anut" 62 threaded on its lower section 26"and which bears against a spring 63 which, in turn, bears against thecasting 5. The: other holding point forthemember 25 ista ring-6.5 whichis internally threaded to cooperate withtheexternal threads of portion21' of the member 25. The ringf65 has on its outer-surface gear. teethwhich mesh with the'teeth of a pinion gear 61. The ringisi fitted in arecess in the inner surface: of casting 5 to prevent longitudinalmovement. The gear 61 is mounted in the extension 6 of the casting 5 andi rotatable when a shaft 58, on which it is mountedis turned in anysuitable manner; such as by a screw driver placedin a slot 69; Thus, toobtain Vernier control of" the vertical adjustment, it is only necessaryto-turn the shaft 58' and the member 25 will be raised and lowered withrespect to the casting 5. Be cause of the small pitch of the threadsbetween the portion 25 and the ring 65, these. members are self-locking,particularly in view of the tension of' the spring 53 which alsoprevents any backlash in the threads.

Extensions and 8 are provided on the casting 5, for mounting opticalelements such as a; prism H on the end of a in 12. The prism re fleetslight from the filament 2| to a monitoring screen to indicate the properpositioning ofthe filament 2| with respect to the optical axis 22,

The above mount is also provided with a releasing mechanism but sincethis construction is disclosed and claimed in S. E. Bartelsons,copending application Serial No. 694,038, filed August 30, 1946, nowPatent No. 2,471,190, issued May 24, 1949, it will be only brieflydescribed herein. The releasing mechanism consists. ofa hand lever 15 inthe form of a crank which extends under the plate 5?. On thehorizontalportion of the crank 15 are two extending rods or fingers :15 and H, theends of which may be forced upwardlyagainst the plate 4i when the end ofthe .C aink is moved in one direction. When this occurs the plate 41 ismoved upwardly against the ten sion of the springs 54 and 55thusreleasing the pressure of the heads 5| and '52 on the prefocus ring '51of the lamp. This permits the; lamp i5 to be easily turned so thatthelar e portions of the slots 58 are under the heads 5| and 52, thusfacilitating the removal of the lamp 15 from the mount.

I claim:

1. An adjustable mount for alight source comprising a casting having anopening therein, a member rotatably fixed bu axially adjustable in saidopening, a holder for a lamp positioned on the upper part of saidmember, said upper part being externally threaded, a ring threadedlyinterconnecting said externally threaded part, said ring having itsopposite sides in contact with the sides of a groove in said casting toprevent an axial movement of said ring, and means geared to said ringfor rotating said ring to axially adjust said member with respect tosaid casting.

2. A lamp mount in accordance with claim 1, in which said casting isprovided with elongated holes to permit initial longitudinal androtational translation of said casting.

3. A mount for permitting Vernier adjustment of the filament of a lampcomprising a casting having an opening therein, a member positioned insaid opening and adapted to be moved along the axis of said opening,means for preventing relative rotation between said casting and saidmember during axial movement of said member, means mounted within saidmember for supporting a lamp, a collar threaded to one end of saidmember, said collar having its sides in contact with the sides of agroove in said casting to prevent axial movement of said collar in anydirection, a nut threaded in the other end of said member, a springbetween said nut and said casting, and gear means for rotating saidcollar to move said member axially in either direction in said opening.

4. A mount in accordance with claim 3, in which a base is provided forsaid casting, together with means for attaching said casting to saidbase, said last mentioned means permitting ini- 6 tial movement of saidcasting with respect to said base within predetermined limits.

5. An adjustable mount comprising a casting having an opening therein, arotatably fixed but axially movable member within said casting, a not onone end of said member, a spring between said nut and said casting fortensioning said member to urge said member in one direction in saidopening, a ring threaded on the other end of said member, said ringhaving its opposite sides in contact with the sides of a groove in saidcasting to prevent axial movement of said ring in any direction, meansgeared to said ring for rotating said ring and for moving said member ineither of two directions in said opening, and means for providing for aninitial longitudinal and rotatable adjustment of said casting.

6. An adjustable mount in accordance with claim 5, in which said lastmentioned means includes tightening screws in oversized elongated holesin said casting.

JAMES LAWRENCE PETTUS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,602,898 Godley Oct. 12, 19261,674,012 Jording June 19, 1928 1,779,953 Sklarek Oct, 28, 19302,014,076 Wellman Sept. 10, 1935

